This invention is directed to a drive axle outer end and, more specifically to a multiple disc friction brake assembly for a drive axle outer end of the planetary reduction type.
Planetary reduction outer ends are used as the final drive in axles for many heavy duty, off-highway type vehicles which are employed in the construction, logging and mining industries, as well as in farming and for mobile materials handling equipment and heavy industrial machinery. As in conventional vehicles, brake mechanisms are associated with the drive axle outer end to restrain rotation of the final drive mechanism and the wheel or sprocket driven thereby. One such planetary outer end employing a drum type friction brake is disclosed in U.S. Pat. Nos. 3,042,145 and 3,150,532 which issued to L. A. Bixby on July 3, 1962 and Sept. 29, 1964, respectively.
A multiple disc friction brake arranged to restrain rotation of a differential shaft input to a planetary gear reduction provided in the differential housing of a drive axle is disclosed in U.S. Pat. No. 3,382,952 issued to G. Grattapaglia on May 14, 1968. Another multiple disc brake assembly arranged to restrain rotation of an input shaft to a planetary gear reduction drive train is disclosed in U.S. Pat. No. 2,953,040 which issued to H. W. Christenson et al on Sept. 20, 1960. In the foregoing disclosures the multiple disc friction brakes engage the input shaft to the planetary reduction upstream of the shaft input to the reduction gearing. Those brakes will therefore not restrain rotation of the reduction gearing for the output member driven by that gearing if the axle or input shaft breaks between the rotor friction discs and the input to the planetary reduction gearing. The multiple disc friction brakes disclosed in the foregoing patents are also remote from the final drive output member and restrain rotation of that member only through the gear reduction and shafts drive connecting the planetary gear reduction and the output member. Thus, those brake mechanisms would also be ineffective in the event of failure of the shaft drive connecting the planetary gear reduction and the output member.
The failure of a drive shaft, whether it be an axle shaft serving as an input to the final drive or a stub shaft directly driving an output member, is not an uncommon occurrence in drive axles for heavy duty equipment. It is therefore advantageous to have the brake mechanisms provided to such drive axles operative on the final reduction gearing and the output member independently of the input shaft and any shaft drive connecting the reduction gearing to the output member.